In any civil Christian society there are certain words which, because they profane some aspect of the body, soul, or mind, are considered vulgar.

Because many in our society, especially parents, don't catechize their children in proper Christian ways, they can be lead into a type of moral relativism by today's pop culture.

Moral relativism is where the individual decides what is right and what is wrong. In this heresy, there are no moral absolutes or truths that are universally accepted. Each person has their own set of truths and if one set of truths infringes on another's set of truths, then the more powerful or influential person's set of truths wins out, even if their set of truths are morally corrupt and are contrary to basic Catholic Christian principles.

In our current sex-saturated culture, I would say people make words bad, in the sense that they change the meaning of a word from what it has always meant to mean to what they would like that word to mean. The best example I can think of is gay marriage.

There is no such thing as gay marriage. Life-long gay partnership, yes, but this is not marriage.

Why?

Because marriage is a Christian sacrament that came solely from the Catholic Church that by nature: